A gas turbine combustor is provided with a transition piece configured to send high temperature combustion gas to a turbine. Patent Document 1 describes a structure in which two types of cooling passages are formed in a wall portion of a transition piece to cool the wall portion of the transition piece.
The first cooling passage is formed in an upstream region of the transition piece located on the upstream side of the flow direction of the combustion gas flowing through the transition piece. In the first cooling passage, air in a casing inner space of the gas turbine where the transition piece is disposed is introduced to the upstream region of the transition piece as first cooling air. Accordingly, the first cooling passage includes a supply port that opens to the outer peripheral surface of the transition piece for introducing the first cooling air.
The second cooling passage is formed in a downstream region of the transition piece located on the downstream side of the flow direction of the combustion gas opposed to the upstream region described above. In the second cooling passage, a portion of compressed air compressed by a compressor of the gas turbine is introduced to the downstream region of the transition piece as second cooling air. The second cooling air, after being introduced to the second cooling passage to cool the downstream region, is discharged to the casing inner space of the gas turbine where the transition piece is disposed. Accordingly, the second cooling passage includes a discharge port that opens to the outer peripheral surface of the transition piece for discharging the second cooling air to the casing inner space. The discharge port of the second cooling passage is disposed downstream of the supply port of the first cooling passage in the flow direction of the combustion gas. The air discharged from the discharge port is the second cooling air heated by cooling the transition piece to become high temperature air.
Patent Document 1 also describes providing a partition wall disposed between the supply port of the first cooling passage and the discharge port of the second cooling passage. The partition wall protrudes from the outer peripheral surface of the transition piece, and is configured to prevent the high temperature air discharged from the discharge port of the second cooling passage to the casing inner space from entering the first cooling passage from the supply port.